Illumination devices for night-vision technology as target illuminators have long been known. They permit high-contrast image production even when the available light is insufficient. With the use of active infrared illumination, unnoticed observation of people and animals is possible owing to the high sensitivity of night-vision devices in the near infrared range.
Generic illumination devices use a diode (LED) emitting light in the infrared range and having a down-circuit collimation optical system. However, the efficiency of LEDs is lower in comparison with the efficiency of, for example, laser diodes and hence the energy consumption is correspondingly higher at the same radiant power. Furthermore, illumination of a target under difficult conditions, such as mist, by means of such illumination devices is poorer than is desirable and possible in principle. Moreover, owing to the very divergent radiation characteristic of an LED, the optical design of such illumination devices is complicated.
A further known possibility is the use of a laser diode as a source of the illumination device. However, owing to the resultant radiation intensity and radiation characteristic, laser infrared illumination systems known to date either constitute a considerable danger to the eye and are therefore classified as laser class 3B according to the standard DIN EN 60825-1 2001-11, for example in Germany, or provide weak illumination. In the case of laser systems of laser class 3B, the emission of optical and acoustic signals is required on putting into operation, inter alia as a radiation warning. Use of a laser illumination device of laser class 3B in conjunction with night-vision devices which, inter alia are intended to permit unnoticed observation of people and animals is therefore not suitable and contradicts the actual purpose of the arrangement.